A significant number of individuals in the U.S. are affected by diseases and injuries that give rise to a troublesome condition called foot drop. Diabetes mellitus, dysvascular diseases, peripheral neuropathies, and other conditions render some individuals unable to lift their foot effectively during their gait cycle, leaving them susceptible to falling or injury. Currently, ankle-foot orthoses (AFOs) are commonly used to orient the foot more favorably for ambulation, and functional electrical stimulation techniques are also being tried with some success. For some individuals, however, these approaches are not suitable or involve unacceptable medical risks. An attractive solution is an externally worn, easily donned system that restores coordinated powered ankle dorsiflexion in time with the wearer's natural gait cycle. In this three phase research program, ADA will leverage previous successful research with electroactive polymer actuators to develop such an ankle dorsiflexion system. Through earlier research funded by the NIH, ADA has demonstrated that its modular bioactuator technology-effectively prosthetic muscles-can power full-scale human upper-limb prosthetic appliances. The natural extension of this work to address the problem of foot drop was originally suggested by ADA'S network of supporting clinicians with the concurrence of the NIH's technical reviewers. In Phase I, ADA will demonstrate the technical feasibility of using electroactive polymer actuators to dorsiflex a simulated human ankle. Phase II will encompass the development of a complete functional system and clinical performance validations using human volunteer subjects. Commercialization will follow in Phase III, with the release of an ankle dorsiflexor product clinicians can prescribe for patients affected by foot drop. [unreadable] [unreadable]